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Commonwealth Aircraft Corporation CA-1 / CA-3 / CA-5 / CA-7 / CA-8 / CA-9 / CA-16 / CA-20 Wirraway 
The Wirraway had been the first product of the Commonwealth Aircraft Corporation formed in 1936 by several of the largest industrial concerns in Australia. To gain manufacturing experience, it had been decided to acquire a licence to produce an aircraft suitable for advanced training and as a replacement for RAAF Hawker Demons.
An Australian Air Board Technical Commission visited the USA and evaluated the North American NA-16, ordered into production for the USAAC as the BT-9 (NA-19) basic trainer.
At the time of the Australian Commission’s visit, North American was working on a development of the BT-99 with a 600 hp Pratt & Whitney R-1340, retractable undercarriage and armament provision as a basic combat trainer. Designated NA-26, this aircraft fulfilled the Australian requirements, although there was disagreement over the need for retractable undercarriage. As a result, two versions of the A-26 were offered to the Australians, the NA-32 (NA-16-1A) with fixed undercarriage, and the NA-33 (NA-16-2K) with a retractable undercarriage, and in 1937, negotiations for manufacturing rights in both the NA-32 and NA-33 were completed, and an order placed for one of each.
The NA-32 was completed in July 1937, although it was not taken on charge by the RAAF until 8 November 1938, and by that time, the NA-33, which had been completed in September 1937 and taken on charge by the RAAF on 2 February 1938, had already been selected for Australian production. With minor changes to suit it more closely to RAAF requirements and Australian operating conditions, the NA-33 was ordered into production for the RAAF as the A20, the Commonwealth Aircraft Corporation applying the designation CA-1 to the type, and the name Wirraway being adopted.
The NA-16-2K changes including a reinforced sub-structure consistent with the rigors of the bombing role and improved offensive/defensive capabilities by the inclusion of 2 x 7.7mm machine guns as opposed to the NA-16's sole gun.
 CA-1 Wirraway A20-21, A20-22 and A20-23 of No.21 Sqn
Production of the initial aircraft was handled out of the Commonwealth Aircraft Corporation (CAC) facility at Fisherman's Bend in Victoria.
CAC designations for Wirraway orders included CA-1, -3, -5, -7, -8, -9, -10 (a bomber version which was cancelled), -10A (dive bomber), and -16. The designation CA-20 covered the conversion of Wirraways for the RAN. 
The Wirraway was a low-wing monoplane assemblies with sweep back and curved wingtips, mounted well forward of amidships. Wings were attached to the oblong, rounded airframe. The engine was held in the forward most compartment and was of an air-fed radial type. The cockpit was held aft of the wings with adequate views from under the heavily framed "greenhouse-style canopy. The empennage was conventional and tapered off to form the base of the rounded vertical tail fin. Horizontal tailplanes were situated at the forward base of this single vertical fin. The undercarriage was of the "tail-dragging" arrangement dominated by the two single-wheeled main landing gear legs. While these twin assemblies retracted into the aircraft, the diminutive single-wheeled tail wheel did not and remained exposed whilst the aircraft was in flight. Crew accommodations amounted to two personnel made up of the pilot and an observer.
The Wirraway’s structure comprised a welded chrome-molybdenum steel-tube fuselage with light metal-covered decking and underside, the sides having fabric covered light-alloy frames; a single-spar wing with spaced ribs and metal stressed-skin covering, and fabric-covered dynamically-balanced ailerons and split trailing-edge flaps, and a tail assembly consisting of metal-covered fixed surfaces and fabric covered moveable surfaces.
All fuel was housed in two 46 Imp.gal tanks in the wing centre section. The main undercarriage members were hydraulically operated, retracting into wells forming extensions of the leading-edge roots. The tandem cockpits were enclosed by sliding canopies, full dual controls were installed, the rear seat could be folded and rotated, and a prone bombing position was provided in the floor. Racks beneath the wing centre section could carry 8.5 lb or 11.5 lb bombs and marker flares, and provision was made for mounting two 0.303-in Vickers Mk.V machine guns in the forward upper decking, the pilot being provided with a ring-and-bead sight, and a Vickers Mk.1 0.303-in could be mounted in the rear cockpit.
Early Wirraways were powered by imported Wasp S1H1-G engines, but this engine was subsequently licence-built by CAC (680 single row Wasps eventually being produced), and the three-bladed Curtiss electric controllable pitch airscrews were produced from 1940 by de Havilland Aircraft at Alexandria, NSW.
Top speed was roughly 220 miles per hour with a cruise speed of just 155 miles per hour. Fuel was limited to 116-US gallons in wing fuel tanks with a pair of 11-US gallon reserve fuel tanks. Dimensionally, the aircraft sported a wingspan of 43-feet even with a length of 27 feet, 10 inches. Her height was 8 feet, 8 3/4 inches. When empty, the Wirraway displaced at 3,992 lbs and 6,595lbs for a maximum take-off weight.
The Wirraway was produced in seven major marks beginning with the CA-1. The initial contract called for 40 CA-1 Wirraways (A20-3 to -42) powered by the Wasp R-1340 S1H1-G of 600 hp, and the first aircraft of this contract (A20-3) was flown on 27 March 1939 at Fisherman’s Bend by Flt.Lt. L.H. 'Boss' Walker. Production of the initial aircraft was handled out of the Commonwealth Aircraft Corporation (CAC) facility at Fisherman's Bend in Melbourne, Victoria. The first three RAAF Wirraways were accepted in July 1939. By December 1940, seven aircraft were being delivered weekly, and by September 1941, 45 Wirraways per month were coming off the production line.
The initial contract had been supplemented by the spring of 1940 by orders for 60 CA-3 Wirraways (A20-43 to -102) which differed externally from the CA-1 in having an enlarged oil cooler beneath the engine. The CA-3 was wholly similar to the CA-1, just assigned a different designation due to the nature of the Australian government production contract. This mark numbered 60 examples in all. In fact, the CA-5, CA-7, CA-8 and CA-9 were all also similar in scope to the original CA-1. The CA-5 was produced in a further 32 examples (A20-103 to -143) embodying minor instrumentation and equipment changes.
The CA-7, CA-8 and CA-9 marks were produced in totals numbering 100 (A20-135 to -234), 200 and 188 examples respectively. CA-7 Wirraway production attaining a rate of seven per week by the end of 1940. By this time further orders had been placed with the CAC calling for 200 CA-8 Wirraways (A20-436 to – 635) and 188 CA-9 Wirraways (A20-636 to -823), these each introducing small changes, such a the repositioning of the carburettor air intake, additional wing racks, etc. The CA-10A was an uncompleted bomber proposal, fitted with dive bomber wings but the CA-3, CA-5, CA-7 and CA-9 models were ultimately modified with such wings to become the CA-20 mark. CA-16, the last production Wirraway, was built to the tune of 135 examples before the last rolled off of the Commonwealth assembly lines and these represented the largest modification since the inception of the CA-1.
 CA-9 A20-622 flown in the summer of 1942
The initial orders for 620 aircraft, production rate attaining 45 aircraft per month in September 1941, and was completed by June 1942, but limited production continued until 1946 when the 755th Wirraway, A20-757, was delivered. The exigencies of the times had resulted in an order for a further 150 Wirraways of the modified CA-16 version (A20-1075 to -1224) intended for the dve-bombing role, although only 135 of these were to be delivered to the RAAF.
Earlier proposals for dive-bombing versins of the Wirraway, the CA-10 and CA-10A, had been cancelled, and the CA-16 differed from the standard Wirraway primarily in making provision for larger external bomb loads, racks being fitted immediately outboard of the wing centre section for two 500 lb and two 250 lb bombs which could be carried in addition to the six 8.5 lb or 11.5 lb anti-personnel bombs and eight target-markers. The 1500 lb increase in offensive load necessitated a conmitant reduction in weight elsewhere, and the twin Vickers guns in the forward fuselage decking and the flexible rear-firing gun were removed, and the aircraft was normally flown as a single-seater when maximum bomb load was carried, although the second seat was retained. The CA-16 fitted a pair of dive brakes for dive bombing sorties. The last was delivered on 30 November 1953.
 CA-16
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